•A regional assessment to promote CE in the construction industry is presented.•Four general accepted CE hypotheses are tested in three Swiss regions to identify different boundary ...conditions.•Consider functional areas instead of political areas to promote CE.•CE-policies should be formulated for construction processes.•Financial incentives should be created to promote CE.
National policies are increasingly being introduced worldwide to establish a sustainable economy that includes principles of a circular economy (CE). The construction industry is particularly in focus with such policies, as it is responsible for almost 50% of the worldwide annual resource consumption and waste production. The Implementation of CE policies remains with local actors, and it is important to better understand the regional context of this transition to support policy- and decision-makers.
This paper aims to contribute to the understanding of regional aspects of a CE and identify regional differences in the building materials industry. To identify these different boundary conditions, we formulate hypotheses, which we then test based on various regional case studies. We use an integrated assessment model to assess a regional industry in terms of environmental and economic indicators and combine Material-Flow-Analysis and Life-Cycle-Assessment using an input-output approach.
The results suggest that imports and exports, especially in smaller regions, can hinder the implementation of CE. CE policies should therefore be developed for functional areas rather than political boundaries to effectively manage material flows. This is also in the light of environmental impacts. Consideration of inter-industry linkages in the industry shows that policies should be formulated specifically for the construction processes, as they have the greatest leverage for policy-induced changes within the industry. The financial analysis shows that incentives should be created to minimize the extraction of primary raw materials and to avoid the landfilling of demolition and excavation material.
Abstract
A transformation towards a bioeconomy is needed to reduce the environmental impacts and resource requirements of different industries. However, considering the finiteness of land and ...biomass, such a transition requires strategizing resource and land allocation towards activities that yield maximum environmental benefit. This paper aims to develop a resource-based comparative indicator between economic sectors to enable optimal use of biobased resources. A new methodology is proposed to analyze the climate effectiveness of using straw in the agricultural, energy and construction sectors. For this purpose, avoided and delayed emissions are analyzed for different use cases of straw and then compared. Considering only avoided emissions, the use of straw as a feedstock for bioelectricity has the highest climate effectiveness (930 kg CO
2
eq./t
straw
). Considering only temporal carbon storage, straw-based insulation in buildings has the highest climate effectiveness (881 kg CO
2
eq./t
straw
). Combining avoided and delayed emissions, the use of straw-based insulation has the highest climate effectiveness (1344 kg CO
2
eq./t
straw
). Today EU-Policies incentives the use of straw in the agricultural sector and the energy sector, neglecting the benefit from its use in the construction sector. The results can support policymakers’ trans-sectoral incentives, where agriculture by-products are diverted towards the use of biomass that most boost economic activities and trigger maximum environmental benefit, given the local circumstances.
The aim of this paper is to study the influence of the deflocculation/flocculation process on the cohesion of clay-based materials by investigating the changes in their internal structure. Indeed, as ...the cohesion of earth materials finds its origin in the capillary forces between clay particles, strongly linked to the porosity of the material, the relationship between the additives, porosity and compressive strength must be understood. The fresh state properties and hardened state properties of the clay mortars, mix designed with different types of mineral additives (phosphate-based as a dispersant and calcium and magnesium based as a coagulant), were determined and compared to those of their micro- and macrostructure based on thermal gravimetric analysis. The results show that the dispersant has a strong impact on the compression strength of clay-based materials due to the optimized organization of the clay particles during the deflocculation step, leading to an increase in the capillary force intensity. Experiments confirm that coagulants decrease the global porosity and compression strength according to their solubility and reaction time. When the reaction between the dispersant and the coagulant is slow, the benefit of the dispersant on clay platelet organization, which influences the mortar stiffness and global porosity, is maintained, and the final strength is high. The TGA confirms that the coagulant has no impact on the microporosity and that the earth material returns to its initial state. Finally, guidelines for mixing and pouring can be highlighted to maximize the strength of poured earth without the addition of hydraulic binder.
Building renovation is urgently required to reduce the environmental impact associated with the building stock. Typically, building renovation is performed by envelope insulation and/or changing the ...fossil-based heating system. The goal of this paper is to provide strategies for robust renovation considering uncertainties on the future evolution of climate, energy grid, and user behaviors, amongst others by applying life cycle assessment and life cycle cost analysis. The study includes identifying optimal renovation options for the envelope and heating systems for building representatives from all construction periods that are currently in need of renovation in Switzerland. The findings emphasize the paramount importance of heating system replacements across all construction periods. Notably, when incorporating bio-based insulation materials, a balance emerges between environmental impact reduction and low energy operation costs. This facilitates robust, equitable, and low-carbon transformations in Switzerland and similar Northern European contexts while avoiding a carbon spike due to the embodied carbon of the renovation.
The increasing pressure to reduce greenhouse gas emissions from buildings has motivated specialists to develop low-carbon products incorporating bio-based materials. The impact of these materials is ...often evaluated through life-cycle assessment (LCA), but there is no clear consensus on how to model the biogenic carbon released or absorbed during their life-cycle. This study investigates and compares existing methods used for biogenic carbon assessment. The most common approaches were identified through an extensive literature review. The possible discrepancies between the results obtained when adopting different methods are made evident through an LCA study of a timber building. Results identified that land-use and land-use-change (LULUC) impacts and carbon-storage credits are not included in most existing methods. In addition, when limiting the system boundary to certain life-cycle stages, methods using the –1/+1 criterion can lead to net negative results for the global warming (GW) score, failing to provide accurate data to inform decision-making. Deviation between the results obtained from different methods was 16% at the building scale and between 35% and 200% at the component scale. Of all the methods studied, the dynamic approach of evaluating biogenic carbon uptake is the most robust and transparent.Practice relevanceThis critical review identified key methodological differences between the most commonly used methods and recommended standards for biogenic carbon accounting in buildings. This indicates a lack of consensus and guidance for conducting LCAs of bio-based construction products and buildings using bio-based materials. A case study applying four different LCA approaches on a timber building identified the inability to compare results and create proper benchmarks. Moreover, different methods lead designers to pursue different strategies to reduce a building’s carbon footprint. Regulators, the construction industry and the construction products industry are directly affected by this lack of comparability. This research highlights the flaws and benefits of commonly used methods. A clear and grounded recommendation is for practitioners to adopt dynamic biogenic carbon accounting for future assessments of bio-based materials and buildings.
The close relationship between crustal magmatism, an expression of heat dissipation, and tectonics, an expression of stress dissipation, leads to the question of their mutual relationships. Indeed, ...the low viscosity of magmas and the large viscosity contrast between magmas and surrounding rocks favor strain localization in magmas, and then possible “magmatic” initiation of structures at a wide range of scales. However, new data about 3-d pluton shape and duration of pluton construction perturb this simple geological image, and indicate some independence between magmatism and tectonics. In some cases we observe a direct genetic link and strong arguments for physical interactions between magmas and tectonics. In other cases, we observe an absence of these interactions and it is unclear how magma transfer and emplacement are related to lithospheric-plate dynamics. A simple explanation of this complexity follows directly from the pulsed, incremental assembly of plutons and its spatial and temporal characteristics. The size of each pluton is related to a magmatic pulsation at a particular time scale, and each of these coupled time/space scales is related to a specific process: in small plutons, we can observe the incremental process, the building block of plutons; in larger plutons, the incremental process is lost, and the pulsation, which consists of a cycle of injections at different timescales, must be related to the composition and thermal regime of the source region, itself driving magmatic processes (melting, segregation, and transfer) that interact with tectonic boundary conditions. The dynamics of pulsed magmatism observed in plutonic systems is then a proxy for deep lithospheric and magmatic processes. From our data and a review of published work, we find a positive corelation between volume and duration of pluton construction. The larger a pluton, the longer its construction time. Large/fast or small/slow plutons have not been identified to date. One consequence of this observation is that plutonic magmatic fluxes seem to be comparable from one geodynamic setting to another and also over various geologic time spans. A second consequence of this correlation is that small plutons, which are constructed in a geologically short length of time, commonly record little about tectonic conditions, and result only from the interference between magma dynamics and the local geologic setting.
The fast rate of magma transfer in the crust (on the order of cm/s) relative to tectonic rates (on the order of cm/yr) explain why the incremental process of pluton construction is independent of – but not insensitive to – the tectonic setting. However, in large plutonic bodies, which correspond to longer duration magmatic events, regional deformation has time to interact with the growing pluton and can be recorded within the pluton-wall rock structure. Magma transfer operates at a very short timescale (comparable to volcanic timescales), which can be sustained over variable periods, depending on the fertility of the magma source region and its ability to feed the system. The fast operation of magmatic processes relative to crustal tectonic processes ensures that the former control the system from below.
This paper aims at assessing the return on investment and carbon mitigation potentials of five investment alternatives for the Cuban cement industry in a long-term horizon appraisal (15 years). ...Anticipated growing demand for cement, constrained supply and an urgent need for optimisation of limited capital while preserving the environment, are background facts leading to the present study. This research explores the beneficial contribution of a new available technology, LC3 cement, resulting from the combination of clinker, calcined clay and limestone, with a capacity of replacing up to 50% of clinker in cement. Global Warming Potential (GWP) is calculated with Life Cycle Assessment method and the economic investment's payback is assessed through Return on Capital Employed (ROCE) approach. Main outcomes show that projected demand could be satisfied either by adding new cement plants-at a high environmental impact and unprofitable performance- or by introducing LC3 strategy. The latter choice allows boosting both the return on investment and the production capacity while reducing greenhouse gas (GHG) emissions up to 20-23% compared to business-as-usual practice. Overall profitability for the industry is estimated to overcome BAU scenario by 8-10% points by 2025, if LC3 were adopted. Increasing the production of conventional blended cements instead brings only marginal economic benefits without supporting the needed increase in production capacity. The conducted study also shows that, in spite of the extra capital cost required for the calcination of kaolinite clay, LC3 drops production costs in the range of 15-25% compared to conventional solutions.
This paper focuses on the modification of clay properties with inorganic additives to deflocculate and flocculate inorganic soil for the development of a material that would be as easy to use as the ...current concrete products, but with a much lower environmental impact. Considering that the rheological behaviour of clays is controlled by their surface charge, we first introduce potential determining ions to deflocculate the clay particles and to reduce the yield stress of the earth material. Their efficiency is characterized using zeta potential measurements and rheological tests. We then achieve the flocculation of clay particles by using natural minerals that slowly dissolve in the interstitial liquid and ultimately precipitate calcium silicate hydrate (C-S-H). The precipitation products are identified by X-ray diffraction and the consequences of this delayed precipitation are followed by oscillatory rheometric measurements. Finally, it is suggested that in this process, C-S-H precipitation is not used as a binding vector but as an anti-plasticizer that removes the inorganic dispersant additives.
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